The subject of the present invention is a suspension system with an oscillating, rigid axle, particularly for tractors.
The current tendency to build fast agricultural tractors makes it necessary to provide suspension systems, particularly for the front axles, which ensure the stability of the vehicle together with adequate comfort even when travelling at the relatively fast speeds which are developed nowadays.
There are currently many suspension systems available on the market. A typical example, in the field of which the present invention also lies, is that of systems with oscillating, rigid axles supported by the load-bearing structure of the tractor by means of a sub-frame.
The sub-frame normally defines an articulation point about which the axle can move along a substantially vertical path.
A disadvantage encountered with these devices lies in the fact that they require specific provisions of the load-bearing structure--the so-called "carriage" of the tractor--and are unsuitable for fitting on vehicles which do not have such provision, that is, which are arranged for receiving either conventional oscillating axles or axles provided with suspension.
Another disadvantage lies in the fact that current structural configurations of the sub-frame, particularly with regard to the positioning of the articulation point, define a path of the axle which is not rectilinear but is generally arcuate about the articulation point. This leads to variations in the wheel base or spacing between the axles of the tractor and/or to movements of the axle transverse its vertical axis, which may adversely affect the correct behaviour of the vehicle in motion.